# US 10,310,148 B2 · Systems and methods of aberration correction in optical systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,310,148 B2 - Document ID: US10310148B2 - Status: Granted - Kind: B2 - Application number: 14/280,607 - Filed: 2014-05-17 - Published: 2014-11-27 - Granted: 2019-06-04 - Earliest claimed: 2013-05-22 - Assignees: Finisar Corporation - Applicants: Finisar Corporation - Inventors: Luke Stewart; Glenn Wayne Baxter; Steven James Frisken - Web page: https://patentgrep.com/patent/US10310148B2 ## CPC - G02B 5/18: Diffraction gratings {(holographic optical elements G02B5/32, G03H; integrally combined with optical fibres G02B6/02057; for coupling light guides G02B6/34; integrally combined with optical integrated light guides G02B6/12; grating systems G02B27/44)} - G02B 5/1861: {Reflection gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials (G02B5/1809, G02B5/1828, G02B5/1833, G02B5/1838 and G02B5/1847 take precedence)} - G02B 6/351: {involving stationary waveguides with moving interposed optical elements (G02B6/3538 takes precedence; interposed waveguides G02B6/3502)} - G02B 6/356: {in an optical cross-connect device, e.g. routing and switching aspects of interconnecting different paths propagating different wavelengths to (re)configure the various input and output links (switching polarized beams G02B6/3594; power equalizers G02B6/356 and G02B6/3594; path selecting means H04Q11/0001)} - G02B 6/3592: {Means for removing polarization dependence of the switching means, i.e. polarization insensitive switching (light guides coupling with polarization selective and adjusting means G02B6/27)} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract Described herein is a diffraction grating (1) for use in an optical system. The diffraction grating includes a substrate (2) and an array of elongate diffracting elements (3) arranged in a grating profile across the substrate. The grating profile imparts a predefined phase change to optical beams to at least partially correct the beams for optical aberrations present in the optical system. ## Claims ### Claim 1 A diffraction grating for use in a multi-wavelength channel optical system comprising a plurality of individual wavelength channels, the grating including: a substrate; and an array of diffraction elements written onto the substrate and having a spacing of adjacent diffraction elements defined so as to spatially separate the individual wavelength channels from an incident optical beam, wherein each diffraction element comprises a curvature across the face of the grating, and wherein the spacing of adjacent diffraction elements and the curvature of each of the diffraction elements across the face of the grating are defined so as to impart predefined phase changes to the wavelength channels to at least partially correct the incident optical beams for optical aberrations present in the optical system. ### Claim 2 (depends on 1) The diffraction grating according to claim 1 wherein the array of diffraction elements defines a phase profile which at least partially reverses aberrations to optical beams by the optical system. ### Claim 3 (depends on 2) The diffraction grating according to claim 2 wherein the spacing of adjacent diffraction elements comprises a spacing of adjacent diffraction elements that varies across the grating in a dimension of diffraction based on the optical aberrations to optical beams present in the optical system. ### Claim 4 (depends on 2) The diffraction grating according to claim 2 wherein the curvature of the diffraction elements comprises a curvature that varies across the grating, relative to the substrate, based on the optical aberrations to optical beams present in the optical system. ### Claim 5 (depends on 1) The diffraction grating according to claim 1 wherein the optical aberration to the incident optical beams includes one or both of optical coma and spherical aberration of the incident optical beams. ### Claim 6 (depends on 1) The diffraction grating according to claim 1 wherein the diffraction elements include grooves, ridges or slots physically defined in the substrate. ### Claim 7 (depends on 1) The diffraction grating according to claim 1 wherein the predefined phase changes to the wavelength channels are determined by computer simulation of the optical system. ### Claim 8 (depends on 1) The diffraction grating according to claim 1 wherein the substrate is planar. ### Claim 9 (depends on 1) The diffraction grating according to claim 1 wherein the curvature of at least some of the diffraction elements is zero. ### Claim 10 (depends on 1) The diffraction grating according to claim 1 wherein the spacing of some of the adjacent diffraction elements does not vary. ### Claim 11 (depends on 1) The diffraction grating according to claim 1 wherein the array of diffraction elements is written into the substrate. ### Claim 12 (depends on 1) The diffraction grating according to claim 1 wherein the spacing of adjacent diffraction elements as the function of position and the curvature of each of the diffraction elements across the face of the grating are defined based on a pre-calculated phase profile determined through a measurement of the incident optical beam propagating through the optical system. ### Claim 13 (depends on 12) The diffraction grating according to claim 12 wherein the measurement is obtained using real data from a reconfigurable diffraction grating in the optical system. ### Claim 14 (depends on 12) The diffraction grating according to claim 12 wherein the measurement is obtained using a measurement from a simulation of the optical system. ### Claim 15 (depends on 12) The diffraction grating according to claim 12 wherein the measurement is obtained using a phase surface implemented in modeling software. ### Claim 16 (depends on 1) The diffraction grating according to claim 1 wherein the predefined phase changes are calculated by simulation of the optical system. ### Claim 17 A multi-wavelength optical switch, including: at least one input optical fiber port for projecting an input optical beam comprising a plurality of individual wavelength channels from a connected input optical fiber; at least one output optical fiber port for projecting an output optical beam to a connected output optical fiber; a lens and/or mirror for focusing or collimating the input optical beam in one or more dimensions; switching optics for selectively switching the input optical beam along predetermined paths between the at least one input port and the at least one output port; and a diffractive device including a substrate and an array of diffraction elements physically written onto the substrate and having a spacing of adjacent diffraction elements, wherein each diffraction element comprises a curvature across the face of the grating, the array of spaced-apart diffraction elements is configured to: i) spatially separate the individual wavelength channels within the input optical beam; and ii) impose predefined phase changes to the wavelength channels to at least partially correct for optical aberrations to the input optical beam, the output from the diffractive device being the output optical beam. ### Claim 18 (depends on 17) The optical switch according to claim 17 wherein the diffraction elements include grooves, ridges or slots physically defined in the substrate. ### Claim 19 (depends on 17) The optical switch according to claim 17 wherein the diffractive device reduces or removes side lobes in a cross sectional beam spot of the output optical beam. ### Claim 20 (depends on 17) The optical switch according to claim 17 wherein the diffractive device controls a cross sectional spot size of the output beam at the at least one output fiber. ### Claim 21 (depends on 17) The diffraction grating according to claim 17 wherein the curvature of at least some of the diffraction elements is zero. ### Claim 22 (depends on 17) The diffraction grating according to claim 17 wherein the spacing of some of the adjacent diffraction elements does not vary. ### Claim 23 (depends on 17) The diffraction grating according to claim 17 wherein the array of diffraction elements is written into the substrate. ### Claim 24 (depends on 17) The diffraction grating according to claim 17 wherein the spacing of adjacent diffraction elements as the function of position and the curvature of each diffraction element across the face of the grating are defined based on a pre-calculated phase profile determined through a measurement of the incident optical beam propagating through the optical system. ### Claim 25 (depends on 24) The optical switch according to claim 24 wherein the measurement is obtained using real data from a reconfigurable diffraction grating in the optical system. ### Claim 26 (depends on 24) The optical switch according to claim 24 wherein the measurement is obtained using measurements from a simulation of the optical system. ### Claim 27 (depends on 24) The optical switch according to claim 24 wherein the measurement is obtained using a phase surface implemented in modeling software. ### Claim 28 (depends on 17) The diffraction grating according to claim 17 wherein the predefined phase changes are calculated by simulation of the optical system.